The High Mobility Multipurpose Wheeled Vehicle (HMMWV, pronounced humvee) is not a single vehicle, but rather is a family of vehicles and platforms intended to be adapted to a wide variety of military missions. Since the introduction of the basic M998 utility truck in 1985, the HMMWV family has grown to meet new requirements and military challenges.
A1 variants entered production in 1992, with upgraded driveline components, heavy-duty rear springs, an improved brake system, a high-ratio transfer and 2.73:1 front and rear differentials. The A2 configuration included a new 6.5-liter, naturally aspirated diesel engine; an electronically controlled, four-speed automatic transmission; and a redesigned emissions system that met 1995 EPA standards. Other features enhanced user comfort, vehicle maintainability and performance.
Following the original series of HMMWV vehicles, the Heavy Variant (M1097 class) was added with a payload of 4,400 pounds to carry communications shelters and with enough towing capacity to serve as the prime mover for the M119 Light Howitzer. The Expanded Capacity Vehicle (ECV) uses the M1097A2 base configuration with a 6.5-liter 190hp turbo diesel providing payload capacity of 5,100 pounds, used for the M1114 up-armored HMMWV and other versions with payloads that exceed 4,400 pounds. The up-armored HMMWVs provide ballistic and blast protection, originally intended for military police, special operations, and scouts but rapidly increased in numbers for convoy protection in Iraq and Afghanistan. Gunner Protective Kits provide 360-degree protection for the vulnerable roof gunners.
The HMMWV A1 models have improved seating, upgraded electronics and M1097 components across the family. The HMMWV A2 configuration incorporates the four-speed, electronic transmission, the EPA compliant 160hp 6.5-liter diesel engine, new rear seats (similar to front seats used in A1 models), and other improvements.
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